The present invention relates to a combination of a main unit, preferably the engine block of an internal combustion engine, and at least one add-on functional unit, preferably an oil filter or fuel filter or a heat exchanger or an oil mist separator, which can be added on to the liquid-carrying or gas-carrying main unit of which there is at least one; with the liquid or the gas also being able to flow through said main unit; with the main unit as well as the add-on functional unit comprising matching elements of a flange connection when adding the add-on functional unit, by forming at least one liquid or gas supply channel and one liquid or gas return channel, said elements engaging each other so as to provide a tight seal.
Combinations of the type mentioned in the introduction are used in various fields of technology, with motor vehicle construction being one field where such combinations are frequently used. In these combinations there is the aim of being able to carry out the add-on as simply and easily as possible while at the same time providing permanent and reliable tightness of the connection. Generally in wide use and therefore well known are flange connections with area connection flanges which are sealed off by one or several interposed seals whose form is specially matched; said seals being mutually held together by means of several screws. A further combination of the type mentioned in the introduction is known from DE 195 39 918 C1. This publication describes a liquid filter, in particular for oil or fuel of an internal combustion engine, and a suitable filter connection flange which forms part of the internal combustion engine. The sealing faces at the filter connection flange of the internal combustion engine are radial seal faces arranged concentrically in respect of each other and the seals at the -filter housing are radial seals arranged concentrically in respect of each other. While this makes possible simple production and sealing of the connection, these flange connections just like the ones previously mentioned generally known flange connections are associated with the disadvantage that the flange connection elements have to be of considerable stability and rigidity so as to prevent eventual leaks at the flange connection elements due to loads experienced. This problem essentially occurs on the side facing the add-on functional unit, with at least that part of the unit which comprises the flange connection elements, having to be made from metal of adequate stability so as to safely meet the necessary requirements. When compared to a desirable design in a lighter material and in particular in a plastic material, such a design results in increased production costs and increased weight However, producing the respective parts from plastic has hitherto not been possible because if the metal had been substituted with plastic, over time the add-on functional unit would not have been able to withstand the occurring loads, and leaks or more severe damage may have occurred.
It is thus the object of the present invention to provide a combination of the type mentioned in the introduction, which avoids the disadvantages mentioned and which makes it possible in particular to produce a flange connection in a simple way, where permanent and reliable tightness of the connection is ensured, and in particular where the add-on functional unit, instead of being made from a stable metal, can also be made from a plastic material or a metal of lesser stability.
According to the invention, this object is met by a combination of the type mentioned in the introduction which is characterised in that the elements of the flange connection are formed not only by at least two parallel line connection pieces, mutually spaced apart, but also by two congruent line boreholes, and in that the flange connection in its connected state brought about by plugging it together, in addition comprises at least one radial seal arranged between the line connection piece and the associated line borehole.
Advantageously, the combination according to the invention is easy to make, namely by simply plugging it together. Production of the individual flange connection elements, too, is technically simple as it merely involves the drilling of boreholes on one side while on the other side it is merely necessary to provide for line connection pieces which are preferably all of identical design so as to simplify production thereof. In the combination according to the invention, the liquid pressures or gas pressures occurring when operating the combination, now have only a very slight effect on the quality and durability of the connection and its tightness. For, as a result of the smaller areas of the flange connection being exposed to pressure during operation, the loads occurring are respectively reduced. By using radial seals in all connections, their tightness does not depend on the axial forces applied; correspondingly only slight axial forces are required to hold the add-on functional unit to the main unit. To do so, e.g. fewer screws and/or weaker screws are now adequate; similarly it is not as a rule possible to do without metal sleeves embedded in the plastic, for attaching these screws. Thus it is now possible to use lighter materials than those stable materials which were hitherto used, in particular it is now possible to use plastics for producing the add-on functional unit. Apart from plastic, the light metal magnesium is a suitable material which is less strong than aluminium, but in the case of the combination according to the invention, due to the particular design of the flange connection elements, this is no disadvantage. The number of the channels routed through the flange connection according to the invention, as well as the media conveyed in those channels, depends on the purpose and the function of the combination. The invention it possible to achieve saving in weight and costs, which savings are particularly important in the production of vehicles.
Preferably, the line connection pieces are provided on the add-on functional unit while the line boreholes are provided on the main unit. In this way, production only requires simple cutting removal processes whereby only a relatively small amount of material needs to be removed by cutting because the flange connection elements are only slightly larger than are the line diameters of the channels which are connected to the flange connection elements.
Furthermore it is preferably provided that the add-on functional unit comprises a housing with a face wall that is flat on the outside, with all line connection pieces protruding the same distance from said face wall, and that the main unit comprises an opposite surface which is flat on the outside, in which all line boreholes are arranged so as to be opposed. Production is sped up and simplified in that all line connection pieces as well as all line boreholes can be made the same.
For securing the add-on functional unit in position after having been plugged onto the main unit, the face wall comprises one or several openings for placing mechanical connection elements, preferably bolts, which can be brought into disengageable engagement with the main unit.
In order to provide exact positioning of the radial seal during add-on and after add-on of the add-on functional unit, it is provided that the line boreholes and/or the line connection pieces each comprise a groove or step for accommodating the radial seal or for providing an end stop for said radial seal.
Preferably, the radial seals are standard O rings with only slight expenditure being involved for each single radial seal. There is thus no need for specially formed seals.
In a development of the invention, apart from a first add-on functional unit preferably an oil filter or fuel filter, a second add-on functional unit preferably an oil cooler or a fuel preheater is provided, with said second add-on functional unit in two separate regions comprising flange connection elements which are designed and arranged such that if required, the second add-on functional unit can be inserted between the main unit and the first add-on functional unit. Advantageously, the combination described here is a modular system which makes it possible to vary the combination without the need for changes in shape or treatment of the units involved.
An alternative embodiment of the combination according to the invention is characterised in that, apart from a first add-on functional unit which is preferably an oil filter or fuel filter, a second add-on functional unit which is preferably an oil cooler or a fuel preheater, is provided; in that said first add-on functional unit is connectable to the main unit and said second add-on functional unit is connectable to the first add-on functional unit, and in that the flange connection elements between the main unit and the first add-on functional unit as well as those between the first add-on functional unit and the second add-on functional unit are of identical construction. Here too there is the option of constructing the combination either with or without a second add-on functional unit. If the second add-on functional unit in the combination is not required, the provided flange connection elements of the first add-on functional unit can simply be closed off. If required, after removal of the closures, subsequently it is possible also to add the second add-on functional unit.
To prevent mechanical overload of the flange connection elements of the second add-on functional unit, as it can in particular occur in moving vehicles, it is useful if the second add-on functional unit comprises at least one support and attachment element arranged at a distance from its flange connection elements which is mechanically connectable via disengageable connection means, preferably bolts, to the main unit or to the first add-on functional unit.